In the medical field, closures for receptacles such as medicament vials must necessarily meet certain strict and reliable criteria. The purity and sterility of the contents of a medicine vial can only be maintained with a closure device that insures a positive seal against the ingress or egress of air or fluids. Likewise, the components of the closure must be capable of providing an aseptic environment with respect to those components which become exposed when the closure assembly is manipulated immediately prior to use. This use usually comprises the insertion of a syringe needle through a septum or stopper, as employed to withdraw a measured amount of the medicament, prior to administering a dosage to a patient.
The need exists for a readily installable closure assembly wherein an improved unitary cap device cooperates with a stopper member to provide a positive interlock therebetween and form an isolated area within the center of the stopper, while a skirt on the cap device is displaced inwardly beneath a rim formation on the vial to retain the components in the assembled condition. By forming the unitary cap device of a molded plastics composition, and which includes a sliding lock sleeve to achieve the final assembly of the closure, the need for a crimping apparatus is avoided and a more reliable, consistent attachment is obtained, compared to those closures utilizing aluminum caps.